The clinical question of mepolizumab in the long-term treatment of idiopathic chronic eosinophilic pneumonia; how long should we use mepolizumab?

The efficacy of mepolizumab as an alternative to glucocorticoids for treating idiopathic chronic eosinophilic pneumonia (ICEP) has been reported. However, various questions remain unanswered, such as the most appropriate dose and dosage interval of mepolizumab for ICEP, how long efficacy is maintained, how long administration should be continued, and whether and when discontinuation can be considered. We present herein three cases of refractory ICEP treated with mepolizumab at a dose of 100 mg every 4 or 8 weeks. No recurrences were observed after 77 months of treatment in Case 1 and after 45 months in Case 2. Case 3 was treated with mepolizumab for 33 months, but ICEP relapsed 42 months after discontinuation of mepolizumab. In conclusion, mepolizumab for refractory ICEP should be continued for as long as possible, considering disease status, glucocorticoid-related adverse events, and the financial situation of the patient.